1. Field of the Invention
The present invention relates to a structure for mounting a base plate made of a synthetic resin and having a shift lever mechanism of an automatic transmission, on the floor of a vehicle such as an automobile, etc.
2. Description of the Related Art
A shift lever device used for a vehicle on which an automatic transmission is mounted has a shift lever mechanism which is supported on a base plate made of a synthetic resin, and which is used to change a shift lever position to any one of a parking position, a reverse position, a neutral position, and a drive position. The base plate has a plurality of through holes for passing respective bolts therethrough. The base plate is mounted on the floor of a vehicle by inserting the bolts into their corresponding through holes and causing the bolts to threadedly engage with corresponding nuts welded in advance on the vehicle floor.
When the base plate made of the synthetic resin is fastened directly with bolts, it is destroyed or deformed by the fastening torque of each bolt. Therefore, the fastening force of each bolt is restricted by the insertion of metallic collars into the through holes, whose respective ends extend axially with respect to the bolts.
When it is desired to mount the base plate on the floor, the through holes referred to above include some which are different in diameter from one another so that the base plate may be moved as needed to enable the positioning of the base plate on the floor. When through holes for bolts are defined in the four corners of a base plate shaped substantially in the form of a rectangle, for example, one of these through holes is defined as a circular hole having a diameter capable of accommodating one of the collars whose inside diameter coincides with the axial diameter of one of the bolts. In addition, the other of these through holes defined at the diagonally opposite corner with respect to the circular one accommodating the collar referred to above is defined as an elongated hole whose longitudinal dimension corresponds to a diagonal line between the two holes mentioned thus far in such a way that any variation in the position of the bolt which passes therethrough can be absorbed or eliminated and the base plate can be reliably positioned on the floor. Furthermore, each of the remaining two through holes is defined as a large-diameter circular hole in such a way that each bolt is loose-fit therein. In addition, three kinds of collars have been fabricated according to the above-described three kinds of through holes for the bolts.
The procedure for mounting the base plate on the floor of the vehicle is carried out in the following manner. Specifically, collars of a number of kinds corresponding to each different type of through hole for the bolts are press-fitted into the through holes. Then, a bolt is inserted into the collar which is inserted into and defined in the form of the circular hole defined above, and is caused to loosely, threadedly engage with a corresponding nut welded on the floor. Under this condition, the base plate is pivoted on the attached bolt so as to place the elongated hole in alignment with a corresponding nut welded on the floor. Thereafter, a second bolt is inserted into the collar which is inserted into and defined in the form of the elongated hole so as to threadedly engage the corresponding nut welded on the floor. Then, bolts are loose-fit into the remaining collars each inserted in and defined in the form of the large-diameter circular holes so as to be placed in alignment with the nuts welded on the floor, and the bolts are caused to threadedly engage with their corresponding nuts. Finally, all the bolts are tightened.
The base plate can be reliably mounted at a predetermined position on the floor in this way. In addition, the fastening torque of each bolt to the base plate is kept constant by the corresponding collar.
However, the conventional structure constructed as described above needs various type of collars having shapes corresponding to the different shapes of the through holes. In the case of the above structure, an assembling process is carried out by providing three kinds of collars and holding them in alignment with their corresponding through holes. Therefore, the efficiency of assembly is poor. Since identical components are not used for respective fastening points, the manufacturing cost of the components is increased.